Hyperbranched and highly branched polymer architectures-synthetic strategies and major characterization aspects

Hyperbranched (hb) polymers are a special type of dendritic polymers and have as a common feature a very high branching density with the potential of branching in each repeating unit. The hb polymers prepared by the classical ABx approach as well as the broad variety of A2+B y combinations with the basic principles of the polymerization processes. The reaction involves the typical features of a step-growth reaction of multifunctional monomers and the formed oligomers but without the possibility of crosslinking. Dendritic, terminal, and linear units and one focal unit (A function) should be present in the resulting, highly branched macromolecule. A general method to introduce functional end groups directly during the polyreaction is the addition of a monofunctional compound to an ABx monomer. Thus, hyperbranched aromatic polyamides and polyethers have been obtained using combinations of suitable A2 + B3 monomers when the reaction was stopped prior to the gel point.